Is it incorrect to say

I'm 20 years old next month.

I'm learning through an English app. It says that the sentence above is incorrect and the correct answer is

I shall be 20 years old next month.

There were 4 choices to this question in the app:

I (am/shall/shall be/will) 20 years old next month.

I thought present simple is appropriate there since this tense can be used to describe the future.

  • 9
    You can use future or present. 'Shall' (future) is correct, although rather formal (at least in British usage), 'will' is less formal, and the present (e.g. 'am') is also correct. That app sounds very limited and not very good. Sep 5, 2021 at 11:22
  • 12
    ''I shall be 20 years old next month'' is correct but sounds very ''posh'' and formal. ''I'm 20 years old next month'' is correct as far as I know and sounds much more natural in conversation. Sep 5, 2021 at 19:18
  • 3
    The present tense can be used to describe the future, but such doesn't always sound idiomatic. If you instead use "will" to indicate the future tense, you will almost never sound incorrect.
    – trlkly
    Sep 6, 2021 at 6:27
  • 4
    As a note, my preference would be to use "will" in a sentence like that but the options include "shall be" and just "will". Without the "be" the sentence would be "I will 20 years old next month" which is plain wrong.
    – Eric Nolan
    Sep 6, 2021 at 10:01
  • 3
    @gotube the suggested answer is 'shall be'. 'Shall' on its own is just an option.
    – mcalex
    Sep 7, 2021 at 6:06

5 Answers 5


You certainly can use the present tense (I am, he is, we are, etc) about a scheduled event, and many people do so when discussing a forthcoming birthday. I am sixty tomorrow, I am fifty in March, I am fifty in two years, I am forty in four weeks, I am 35 in a couple of months. You can also say (e.g.) 'I will be 26 in a few weeks', and British users may well use 'shall', which is more formal.

We use the present simple for something scheduled:

We have a lesson next Monday. The train arrives at 6.30 in the morning.
The holidays start next week.
It's my birthday tomorrow.

Talking about the future (British Council)

Wrexham MP Ian Lucas will stand down at next election - 11 Oct 2019 — "I am 60 next year. I have been an MP since I was 40. I think the time is right for me to choose to follow a different path in the years to come" (BBC)

Ex-soldier from Hornchurch in diving world record bid: 14 Feb 2016 — He said: “I am 50 next year and so this is my last chance to get the record. I want to stay underwater for five days." Hornchurch Recorder (Essex newspaper).

On the the more formal side, from the Letters of CH Spurgeon (1834 - 1892), a British preacher and religious writer:

May the everlasting arms be underneath you! I breathe for you a loving, tender prayer,—" Lord, comfort Thy dear servant, and when he departs, may it be across a dried-up river into the land of living fountains!" I am fifty next Thursday, and you are near your Jubilee. In this we are alike; but Jesus is the highest joy. Into the Father's hands I commit you, "until the day break, and the shadows flee away." Your loving brother, C. H. SPURGEON.

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  • 26
    To add, "shall" here is exceedingly formal to the point of being incorrect in modern usage, at least in my (American) opinion. If OP's app says "shall" is the correct answer I would hesitate to trust it on anything else.
    – randomhead
    Sep 5, 2021 at 10:48
  • 21
    @randomhead - to me (I shall be 70 next April), UK (English), middle class, using 'shall' is a little old-fashioned and rather formal but not howlingly archaic and definitely not 'wrong' or 'incorrect'. Cambridge Dictionary quoting English Grammar Today says 'Shall is only used for future time reference with I and we, and is more formal than will'. In July I shall be 50 (The Times, 2018), in another six months, I shall be 50, and, therefore, become entitled to benefit (Hansard - UK Parliamament record, 1964) Sep 5, 2021 at 11:01
  • 20
    I think the formality of “shall” might be a difference between BrE and AmE. In the USA, I almost never hear “shall” used in any context other than legal - certainly not in everyday spoken English. If someone said “I shan’t be pleased” to me, I’d ask them what that quote is from, because I’d never think that’s just someone talking. Sep 5, 2021 at 18:33
  • 1
    Comments are not for extended discussion; this conversation has been moved to chat.
    – Eddie Kal
    Sep 9, 2021 at 7:36
  • As a speaker of AmE who has read a lot of BrE I find "I am 60 tomorrow" odd and not at all idiomatic, and "I am 60 in three months": flatly wrong. I accept that this usage occurs in some parts of the UK, but would still advise learners to avoid it. "I will be 60 tomorrow": is correct in all forms of English. Sep 29, 2021 at 0:28

Want to add to the accepted answer: using the present tense to speak about future events is common, but to my intuitive understanding as a native US speaker is incorrect... except that it's understood to be a shortening of saying "I am/I'm going to be 20 years old next month."

Saying "I will/I'll be 20 years old next month" is overwhelmingly the most correct/normal way to say it in my experience, but saying "I'm 20 years old next month" is perfectly acceptable, because it's understood to imply the absent "going to be".

Resultingly, it'd seem wrong written down in any context besides the most informal and conversational (personal communication/blog posts/anything emulating face-to-face conversation). In professional communication, essays, or in a book (unless it's in dialogue between characters), use of the present tense would be interpreted as either agrammatical or out-of-place due to its informality.

  • 8
    +1 - Native AmE speaker here, and "I'm 20 years old next month" (without the implied "going to be") sounds incorrect enough for me to ask the speaker to clarify/repeat themselves, and might make me question their fluency.
    – A N
    Sep 6, 2021 at 2:05
  • 4
    @A N: Same here. I think almost anyone would say either "I will be..." (hardly anyone uses shall), or "I'm going to be...".
    – jamesqf
    Sep 6, 2021 at 4:15
  • -1: English doesn't have a future tense. There are numerous constructions which talk about the future solely using a present tense construction, such as "I'm visiting my aunt tomorrow." (compare to: "I'm visiting my aunt right now."). You cannot add a "going to" to that sentence without recasting it altogether. There is simply no grammatical requirement to add any sort of marker explicitly indicating the future, because the future is not grammaticalized in English (unlike the past). Insisting otherwise is a hypercorrection.
    – Kevin
    Sep 6, 2021 at 5:51
  • 11
    @Kevin English only doesn't have a future tense if you use a very technical definition of the word "tense" which requires that the word be altered. It very much does have standard constructions that indicate that an action takes place in the future, or that a state will become true in the future. Using the construction "I'm 20 next month" does not use these standard markers. It is something that may occur in colloquial English, but is generally regarded as non-standard grammar, at least, in American English.
    – trlkly
    Sep 6, 2021 at 6:23
  • 1
    Comments are not for extended discussion; this conversation has been moved to chat.
    – Eddie Kal
    Sep 9, 2021 at 7:36

This is a perfect example of how colloquial speech leaves out or contracts redundant words.

Your third quote shows "I am 20..." as acceptable, and "I'm 20..." is merely the shortened (spoken or even lazy) way of saying the same.

Upshot - your app isn't quite smart enough to know they're the same.

  • 1
    I don't think it's even colloquial speech, except perhaps in some dialects.
    – jamesqf
    Sep 6, 2021 at 4:17
  • 2
    @jamesqf perhaps "spoken shortcuts" rather than colloquial. Notice your own comment line contains two abbreviations "I do not think it is even colloquial speech"
    – Criggie
    Sep 6, 2021 at 8:24
  • 1
    Perhaps we're thinking of different things? I didn't mean the contractions, I meant the idea of using present tense for a future state, saying "I'm 20 next month", rather than "I'll be 20 next month". Which itself contracts "I will" (or shall for the pedantic) and "20 years old".
    – jamesqf
    Sep 6, 2021 at 16:22
  • 2
    You missed the point, the app is not saying I am is correct it's just a multiple choice answer and one of the choice was I am which the OP chose and the app told him it was wrong, he is the one who shortened it in his question
    – Tofandel
    Sep 7, 2021 at 10:41
  • 1
    @Tofandel well... that's confusing. Good spotting.
    – Criggie
    Sep 7, 2021 at 11:56

I am 20 years old next month

I have a feeling that the aforementioned construction derives from a very formal way to express a future event that is considered inevitable or expected, e.g:

Soon I am to be 20 years old.
We are to be married in the month of June”

The formula be to + infinitive can be replaced by am/is/are going to + infinitive

Google books revealed the following quotations

  1. To-morrow I am to be arraigned as a culprit; my friends may leave me, my counsel may desert my cause as hopeless, and the world may point at me as a recreant to virtue…
    To love and To Be Loved 1855

  2. “I am very intimate, especially with Matilda: I am to be one of her bridesmaids. You know, of course, that the wedding-day is fixed for to-morrow?” 1853

  3. Tomorrow is to be one of our anniversaries, you know,” she replied; “twenty-four years ago – to-morrow — was to have been to me what to-day is to Linnet. I wonder if I were [sic] as light hearted as Linnet.”

  4. “…for science is inexhaustible; every day opens a glimpse of some fact that tomorrow is to see ascertained.” Significance of the Alphabet By Charles Kraitsir, 1846

Today that line might be written as “that tomorrow sees ascertained” or “that tomorrow will see ascertained.”


The TL;DR version:

"I am 20 years old next month" is incorrect because in that sentence "20 years old" is an adjective which describes you.
Remember that the verb 'to be' plus an adjective is used to talk about the present.

"It is my 20th birthday next month" is correct because the object of the sentence is the birthday, and is a scheduled event in the future.

Original answer follows:

I'm 20 years old next month.

Is understandable but grammatically incorrect, although frequently used colloquially.

Begin edit

As an aside. @Muzer comments that "It's not grammatically incorrect. -1.".

It is incorrect in that form, because if you want to use "I am" to speak about the future then it should be combined with a verb ending in "-ing". Here's how you can use "I am" correctly:

I am going to be 20 next month.

I'm turning 20 next month.

If you're talking about the birthday, as a scheduled event, then you can use the present tense like this:

It is my 20th birthday next month.

For more, see https://learnenglish.britishcouncil.org/english-grammar-reference/talking-about-the-future

End edit

I'll be 20 years old next month.

Is grammatically correct, but in my opinion:

I'll turn 20 next month.

Is the best way of saying what you want to say.

If you're currently 20 then it's not incorrect to say you'll be 20 next month, too; but to say that you will turn 20 suggests that your 20th birthday is next month.

  • 6
    It's not grammatically incorrect. -1.
    – Muzer
    Sep 7, 2021 at 10:01
  • 2
    "Tonight we dine in hell", "eat, drink and be merry for tomorrow we die", etc. - I don't think there's anything ungrammatical here. Indeed look at point 1 in the page you linked yourself. If something is scheduled there's no need for "-ing" or an auxiliary verb.
    – Muzer
    Sep 7, 2021 at 11:07
  • 2
    "Tomorrow we are dead" sounds fine to me. Just like "I'm 20 tomorrow".
    – Muzer
    Sep 7, 2021 at 12:20
  • 1
    You say I am 20 years old next month is grammatically incorrect, then say that It is my 20th birthday next month is fine? Show some consistency! I will be 20 years old next month & It will be my 20th birthday next month Either they're both good using the simple present conjugation of to be, or both bad. To me, they're both fine.
    – CJ Dennis
    Sep 8, 2021 at 11:38
  • 2
    So far, 35 people disagree with you that the accepted answer isn't good. I haven't voted on this question or any of the answers (either up or down), so none of those include me. I will repeat what I said before. Remember, grammar is descriptive, not prescriptive. The fact that enough other native English speakers say it's fine is what makes it fine.
    – CJ Dennis
    Sep 11, 2021 at 1:40

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